my simple compressor of random info

Question

i make a base change from binary but instead of adding the reminder i alternatively add it and substract it:

re:

TextWindow.WriteLine("enter random number to compress")

number=TextWindow.Read()

dectobin()

compresion()
TextWindow.WriteLine(number+" compressed number:")
decompresion()
 
bintodec()
TextWindow.WriteLine(number+" decompressed number: ")

Goto re

Sub bintodec
numero=0
For i=1 To Text.GetLength(number)
    dig=Text.GetSubText(number,i,1) 
    numero=numero*2+dig
  EndFor
  number=numero
EndSub

Sub dectobin
  numero=""
  While number>0
    dig=Math.Remainder(number,2)
    numero=Text.Append(dig,numero)
    number=Math.Floor(number/2)
  EndWhile
  number=numero
EndSub

Sub compresion

numero=0
flag=1
j=0
While j<Text.GetLength(number)
j=j+1
dig=text.GetSubText(number,j,1)
flag=flag*(-1)
  numero=numero*2-dig*flag
'TextWindow.WriteLine(numero)
  EndWhile
number=numero
endsub

Sub decompresion

numero=""
repeat:
savednumber=number
While number>0
 'TextWindow.WriteLine(number)
dig=Math.Remainder(number,2) 

number=(number+dig*flag)/2
flag=flag*(-1)
  numero=Text.Append(dig,numero) 
EndWhile
l=Text.GetLength(number)
If Math.Remainder(l,2)=0 Then
  flag=-1
  number=savednumber
  Goto repeat
EndIf

number=numero
EndSub

  

edit:

actually the program is wrong, i saved without noticing the variable flag